Our invention relates to amplifiers, and more particularly to differential amplifiers capable of producing an output proportional to the difference between two inputs. More particularly, our invention relates to a differential amplifier whose gain is variable at will.
Our invention represents an improvement over variable gain differential amplifiers disclosed by U.S. Pat. No. 3,689,752 to Gilbert. When the gain is varied, their high frequency response characteristics of the prior art amplifiers change so much that the signal waveform suffers great distortions. We will later explain how such signal distortions have occurred with the prior art, with reference to some of the drawings attached hereto.